Duncan, the first patient diagnosed with Ebola in the United States, had been in critical condition at Texas Health Presbyterian Hospital.

The hospital said in a statement that he died at 7:51 a.m. local time Wednesday.

Meanwhile, media reports say the United States will place agents at airports and other entry points to check travelers for signs of Ebola.

The Associated Press said Homeland Security Deputy Secretary Alejandro Mayorkas said Wednesday that U.S. agents will be posted at major points of entry to the U.S.to look for symptoms and hand out information about the Ebola virus.

Mayorkas did not say when the new measures would go into effect.

Border Patrol fact sheets

He said U.S. Customs and Border Protection agents will be handing out fact sheets listing symptoms and instructions on contacting health providers.

Earlier Wednesday, the United Nations mission in Liberia said a second member of its staff has contracted Ebola.

In a statement, the mission said the international medical official is undergoing treatment, but did not specify their nationality. The first infected staff member died last month.

And the World Bank said on Wednesday that the regional impact of West Africa's Ebola epidemic could reach $32.6 billion by the end of 2015 if it spreads significantly beyond the worst-hit countries of Guinea, Liberia and Sierra Leone, the World Bank said on Wednesday.

“The enormous economic cost of the current outbreak to the affected countries and the world could have been avoided by prudent ongoing investment in health systems-strengthening,” World Bank President Jim Yong Kim said in a statement.

The Ebola outbreak has killed more than 3,400 people - with most cases in Liberia, Guinea and Sierra Leone.